---
id: 657f425dbab54e11993c80f0
title: Step 15
challengeType: 20
dashedName: step-15
---

# --description--

So far, in this project you have not seen any usage of list comprehensions whatsoever. Like you learned in the first step, list comprehensions are a more concise way of constructing lists in Python.

Begin the transition to comprehensions by commenting out all the lines of code inside the `convert_to_snake_case()` function. Don't delete them as they'll be helpful when you implement the logic using a list comprehension.

Remember to add the `pass` keyword to the function body to prevent the code from failing during the tests.

# --hints--

You should comment out all the 10 lines of code inside the `convert_to_snake_case()` function and nothing else. Add `pass` to fill temporarily the function body and avoid an error.

```js
({
    test: () => {
        const transformedCode = code.replace(/\r/g, "").replace(/\n#/g, "\n #");
        const convert_to_snake_case = __helpers.python.getDef("\n" + transformedCode, "convert_to_snake_case");
        const { function_body } = convert_to_snake_case;

        assert.equal(function_body.split("#").length - 1, 10);
    }
})
```

# --seed--

## --seed-contents--

```py
--fcc-editable-region--
def convert_to_snake_case(pascal_or_camel_cased_string):
    snake_cased_char_list = []
    for char in pascal_or_camel_cased_string:
        if char.isupper():
            converted_character = '_' + char.lower()
            snake_cased_char_list.append(converted_character)
        else:
            snake_cased_char_list.append(char)
    snake_cased_string = ''.join(snake_cased_char_list)
    clean_snake_cased_string = snake_cased_string.strip('_')

    return clean_snake_cased_string
--fcc-editable-region--
def main():
    print(convert_to_snake_case('aLongAndComplexString'))

if __name__ == '__main__':
    main()

```
